Process of treating foul solutions.



Patented Aug. 20,1918` Punt. oLuTlou *To TANK, Houst.

CELL Il` SoLuTIoN ULPHATL) I F. T. SMITH.` PROCESS OF THEATING FOULSOLUTIONS.

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INVENTUV l (M504 I QMPuR'ITIE-a) N 'l AWV UniTED STATES OFFICE.

raam: r. satira, or mineros-'13min 4ne'simcimsn'rrs.

, Pnocnss or 'mancino roUL SOLUTIONS. i

' Application led April 2,

To all 'wh-0m may concern:

Be 1t known that I,F,RAN1{ T. Stura, a

1 citizen` offthe Unitedv States, residing at AJamaica Plain, in thevcount-'y of SuHolk and State of-Mas'sa`cl1usetts, have invented new anduseful" Iiiiproyements' in the Processes of Treating Foul Solutions, ofwhich the following isaspecication.

ThisinVentiOn relates to the treatment of impure solutions of acid andsalt, such as the'foul solutions of sulfuric acid and copper sulfatearisin incoppenreneries and in thefwinningo nietalsbyl-leaching; Theobject of the process is the production of pure solutions o acid and,usually, salt', utilizingi the acid and salt of the foul solution.W'hen.' this process is applied 'to' foul electrolyteV from copperrefineries it 'has the additional advantage of' simultaneously yieldingvpure copper, concentrating most of the impurities in a 'sludge whichmay be used asa basic 'iu'xi lldleflllng 10W grade metal '(blacl;

copper or speise) when available;

@This process will be described by explaining its application to foul,copper-reiinery` electrolyte, for which it is especially suited.

It consists vof the hereinafter described steps whichmay bemodliiedsomewhat in special cass. AInstead of a relinery electrolyte, the

cleaning iron with sulfuric acid maybe used. 4In the application:Voli/the vprocess ltocopper refinery electrolytethe steps aboverefer-.red to-are aslfollows: 11. The concentration ofcopper in the foulsolution is 'reduced by dilution,"by plating out copper using low-.gradeanodes, or, pref erably, bytreating in the secondstep as' will be exlamedlater.

2. he'foul `solution is thensubjected to electrolysis as follows: 'Itispassed through' anode chambers of electrolytic cells Vcontainingsoluble anodes,while a pure solution of copper sul fate (preferablyacidified'withisuh 'f "rlc acid) fiows throughthe cathode chambers;4vThe anode and cathode chambersare separated by diaphragms in' vorderto `prevent the solutions roni mixing, yet allowlng the l anodes,

through the diaphragmv to the pure solution, f

current of electricity )to f pass through".Y current of electricityel'itersthecells t rough passes from` v the 'foul solution,

and'deposits `metallic copper'on the cathodes. Theieonduction of thecurrent throughthe diaphragme necessitates fthe passing-'fci'hycoppe'rfan'd otherimitals,l in the form y acid solution. o ffcrroussulfate obtained in,

The danger of contaminating the pure cop-- V, spannen@discernment.Patented Aug, 20,1915:

m15. serial N'o; 13,746.

of ions, ,from the anolyte to the catliolyte. The negative ions morethrough the diuphrain'in the opposite direction, but they may edisregarded. The acid is, relatively, highly dissociated, and the hydro'en move about five times as fast as tie other ions, consequently, theywill movethrough the diaphragm at the greatest rate.

These hydrogen ions re lace copper ions deposited on the cathode rom thecopper sulfate in the catholyte, thereby forming hydrogen sul fate, orsulfuric acid. The hydro en ions which lpass through the diaphragm romthe anolyte are replaced bycopper lons 'formed by the'dissolving of theanode, thereb' formv ing copper sulfate. When nearly all of the hydrogenions, (formed by the dissocia xon ofv the' acid originally present inthe Loul solution) havemigratedout of the auoiyte,"'"

the' anolyte is nearly'` neutral and is their treated with aprecipita-nt for iron ashereinafter described. It is to be noted that noacid will be formed at the anodes, since these will be soluble.

e More copper sul-fate is added to the pure .solution if it is 'to beused as electrolyte in the refinery tanks. Usually it will. be advisableto replenish this .solution 'with copper sulfate before it becomes toodilute, :unless it is to be used for some-purpose for which a lowconcentration.. of copper is desirable'. The foul solutln Abecomesricher 1n the' metals of the anode, most-ly copper.' ,The re.; ductionof the gioncentration Vof copperv in this solution is made beforeelectrolysis, since it 4was found on experimenting 'that unless mreduced, the anode becomes coated with cop er 'sulfate 'crystals beforethe acidit' 1sV owerelfV suiciently. The -efzzrflution is ept warm` toallow a higher concentration of copperI sulfate, as well as to savepower,V

It' is obvious that as the ccnceutrationof the acid inthe a-nolytediminishes, the other ions take a more prominent part in conduction, andthe amount -of copper, nickel, and iron passing through the diaphragmwith the hydrogen will be considerable if the concentration of acid istebe reduced quite low.

per` sulfate solution can lbe eliminated, and the concentration o fcopper in the foul so-` lution canbereduced by carrying Aon thenpurification electrolysis in two stages." First,

j the foul" solution (which has not been subjected to any specialtreatment) is usedv as catholyta' and Vfoul solution which has lost mostof its acidity is used as analyte. The anolyte loses the remaining acid,sind copper,

nickel 4and iron to the catholyte. The rate chambers of the first seriesof cells', to the anode ,chambers of thesecond series, in which it losesmost of its acidity. series, pure copper sulfate solution is used as thecatholyte. Thus,'all of the acidity lost by the foul solution'ils'gained ultimately by the ure'copper sulfate solution.

j 3. ien the acidity of the foul solution has been reduced sufficiently,it is passed to precipitation tanks where it maybe treated with oxidsifstill slightly acid, and with ferrous sulfate if there is insuiicientiron pres ent for the subsequent operations. Air is then blown throughthe solution to oxidz"e the ferrous iron (thereby using up anyunneutralized, acid) and to precipitate-basic ferrie salts. If theamount of iron remaining in solution is too high, it is completelyprecipitated with a basic, commercial pre 4 -cipitant for ir'on, such aspowdered limestone, avoiding an excess so that no copper will beprecipitated. The solutionis kept hot to facilitate hydrolysis and tokeep the copper sulfate in solution. The precipitates from theseoperations consist chiefiy oihcalciuin sulfate, ferrie liydroxid basicsalts of' iron, antiinony and bismuth, arsenates vand arsenites. Theyare removed from the so-l lution by filtration or decantation, and maybe briqueted or sintered ywith'fine ore or fine dust, since they containuseful basic letts. This would leave the cob-alt ;.(and, a small amountof nickel and ammonium) in solution, but these would not interfere withits use as electrolyte.

' If this process is used, the-precipitation of the iron may beaccomplished by means of ammonia: thereby forming ammonium sulfate.'Nickelammonium sulfate israther soluble in hot water, so that-the'iron,arsenic, etc., can be removed without this doublesalt...A

In this,

if the; solution is kept hot. Or copper sulfate 'and nickel sulfate maybe separated by crystallization, the copper sulfate being used to obtainthe'required solution of copper sulfate. l

This process was specially devised for Ythe treatment of foul solutionsof copper sul' fate and sulfuric yacid produced in the elec- 'The anodesmay be very impure; black copper or even Speise may be used. In thiscase, more-copper sulfate will be consumed than is produced vin theprocess, Ibut thissalt is v quite cheap. The treatment of the'anode maybe the main object. -In anyrcase the hydrogen ions migrate through adiaphra leaving the lslightly dissociated impurities, and replace themetal in the salt at the cathode. The hydrogen of the acid in the foulsolution is replacedby metal ions from the anode, the solution becomingnearly neutral enough to allow the economical precipitation ofv certainimpurities. l

The invention will now be more fully described, when taken in connectionwith the accompanying drawings, and the novel features 'thereof will bepointed out and clearly 95 defined in the claims at the close ofthisspecification.

The invention hereindcscribed, however, "does not consist of theapparatus itself and therefore the drawings are diagrammatic,

In the drawings, Figurel is-a diagram showing the fiow` of solutionunder treatment when two cells are employed. Fig. 2 is a diagramrepresenting the essential features of the cell. Fig. 3 is a diagramshowing the act-ionin the cell. I f

Referring to the diagram shown in Fig. 1, i

the fouljsolution goes through the following steps. l. It 'flows fromthe tank house into vthe cathode chamber C1, cell I, where it is nearlyfreed from copper. i 2. From C1Xto'A2,cell II, where'it loses bymigration to the cathode chamber C2' 115 most of the hydrogen ions,and'gains copper by the dissolvino of the anode. i

3. From A2 tofA?, cell-I, where it loses most of the remaining hydrogenions', and gainsstill more copper.

4. To a tank in'which the iron is oxidized and precipitated,`togetherwith thearsenidv antimony, and bismuth.

5. Through a filter, or other device to separate the lprecipitate,'to atank for treatment 1425 -Jlonou thecathoddand 'gains acid by mil 180gration of hydrogenions through the diaphragm Where M is a diva-lentmetal (copper, nickel or the like). The hydrogen ions pass l through thediaphragm to the catholyte where the change may be represented by theequation:

,Which/replace the hydrogen ions lost by m'igration. In otherwordstcopper deposits on g the ,'cathode; copper dissolves from thetrolytes composed of solutions of acidand' anode; H* (to a les/s'vextent other ions) migr 'te asfshown by the. arrows.

hat I.4 claim 1s:

1, The,4 process oftreating impure elec- Vtnolytes composed of solutionsot acid and salts, said 4e rocess consisting of electro l zing v-theimpure solution in the anode c amber of an electrolytic cell whichcontainsa 4soluble anode While a solution of pure "copper sulfate flowsthrough the cathode chamber.

`2.- The process of treating impure elecsalts, said process consistingof passing the impure solution through the anode cham-- bei' `of anelectrol. tic cell Which contains a soluble anodewhi elan acidiedsolution of pure copper sulfate flows through the cath- 4ode chamber,the two chambers being separated from each other by a diaphragm.

3. The process of treating impure electrolytes-composed of solutions ofacid and salts, said process consisting of passing the impuresolutionsthrough the anode chamber of an -e'lectrolytic cell which contains asoluble anode while an 'ecidified solution of lpum copper sulfate fiowsthrough the cathode chamber, the two chambers being separated from eachother by a diaphragm, then treating the anolyte with a precipitent andtheir removing the precipitates from the solution.A

4. The process of treating impure electrolytes composed of solutions ofacid and salts, said process consisting of e ectrolyzing the impuresolution in the anode chamber of an electrolytic cell which contains asoluble anode while a solution of pure copper sulfate Hows through thecathode` chamber, then adding an oxidizing agent and a basic precipitantfor iron, then separating the precipitate and treating the solution toleave only pure copper sulfate, then passing the copper sulfate to thecathode chamber of the cell, then passing thesolution to a tank house. Y

5. The process of treating impure solutions of electrolyte,` saidprocess consisting of passing the impure solution `into the cathodechamber of an elcctrolytic cell which is divided into 'an anode and acathode chamber by a diaphragm, the anode` chamber containing a solubleanode, then passing the solution from the cathode chamber of said cellto the anode chamber of a second cell of similar construction to saidfirst cell, and containing a` solubleanode, then causin the solution topass to the anode chamber o l the rst cell, then causing the solution topass from the anode chamber of the first cell to a therefrom all exceptthe pure coppei` suliate, then passing the copper sulfate to the.cathode chamber of the second cell.

6. The process of treating impure solut-ank, then treating the solutionto remove tions of electrolyte, said process consisting of passing theimpure solution into the cathode chamber of an electrolytic cell whichalso contains an vanode chamber having a soluble anode, thev anode andcathode chambers being separated fromeach other by a diaphragm, passingthe solution from the cathode chamber of said cell to the anode chamberof a second cell of similar construction to said first cell andcontaining a solu# ble anode, then causing the portion of the so'-lution which remains in the anode chamber of the second cell to pass tothe anode charm` ber of the first cell, then passing the solui tionwhich remains in the anode chamber of the first cell to a tank, andthere adding an oxidizing agent and a basic precipitant for iron, thenseparating the Aprecipitate and Atreating the solution Ato leave onlypure copper sulfate, then passing the copper sulfate ,to thecathodechamber of the second FRANK T. SMITH.

lVitncsses: V

CHARLES J. MAn'rnLL, FnANoIs FONTAINE.

